Note: Descriptions are shown in the official language in which they were submitted.
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1. Field of the Invention. Thls invention relates
generally to apparatus for drilling a well or bore hole in the
10 earth using a plurali~y of drill pipe sections joined ln end-to-
end relationship with a cutter head or drill on the lowermost
end and relates par~icularly to apparatus for selectively sup-
porting or holding Lhe drill string and assisting in "breaking"
~he connection be~ween pipe sections when the string is being
disassembled.
2 Descri tion of the Prior Art. In the past, most
vertically disposed drill rigs have included a drill table lo-
cated close to the earth and having an opening through which the
drill string extended. These prior art structures usually have
included a clamp mechanism located adjacent to the drill table
and such clamp mechanism was arranged so that a pair of jaws
could be actuated to clampingly engage a pair of opposed flat-
tened portions adjacent to the upper end of each drill pipe sec-
tion. These clamping mechanisms were satisfactory for holding
the drill string; however, it was usually necessary to provide
a separate "break" wrenrh to s~art separation of the upper drill
pipe section from the remainder of the string during disassembly.
The "~reak" wrench has been necessary since each drill plpe sec-
tion usually has a reduced threacled stud which engages a threaded
opening in the end of the next adjacent pi.pe section. During
the drilling operation, the drill string ls rotated in a direc-
tlon to tighten the cooperating screw thread~l The "break" wrench
ordinarily is sufficient to start separation of the drill pipe
~ectlons but ~dhen such wrench fails to break the threaded oonnec~
tion, substantial manu~l labor has been required with t~e
assistance of chains or large stlllson type wrenc~es to break
the threads.
S~me efforts h*ve been made ~o improve the conventional
clamping mechanisms by providing selectively operable holding
wrenches to hold the drill strlng against rotation while the
threaded connection has been broken elther by the power plant
mounted on the drill rig or by a "break" wrench. Some examples
of the prior art are disclosed in the United States pa~ents to
Alexander 3,239,016; Back 3,708,U24; Coyne 3,771,389; and Dyer
Re. 28,351.
The present invention is embodied in a holding wre~ch
including a yoke slidably mounted within a housing and adapted
to be extended and retracted by a fluid cylinder. The yoke has
a generally U-shaped recess in its outer end of a size to re-
ceive the opposed flattened portions of a drill plpe seetion.
The housing is mounted on a rota~able platform carried by the
drill table and is located between a pair of spaced stop members
secured thereto. During the drilling oper~tion, the yoke is ex-
te~ded into engagement with the f~attened portions of the upper~
~ost drill pipe section so that the drill rig power plan~ may
be disconnected from the string to permit another drill pipe
section to be added. When the drill pipe string is being dis-
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assembled after the drilling operation has been completed, orwhen it is necessary to change the drill bit, the power plant
of the drill rig is raised so that the uppermost drill pipe
section is located entirely above the drill table after which
the yoke is extended into engagement with the flattened
portions of the next subjacent drill pipe section. Thereafter
the power plant is operated in a reverse or unscrewing
direction; however, if the connection between the first
and second drill pipe sections does not "break", the rotatable
platform may be moved from one stop member to the other and
then moved rapidly by the power plant in the unscrewing d.irection
to cause the housing to slam into the stop member and break
the threaded connection between the drill pipe sections.
In one aspect, the present invention provides
apparatus mounted on a drill table for selectively prevent-
ing relative rotation between the apparatus and a string of
drill pipe sections connected together in end-t~-end relation-
ship along an axis of rotation, each of said drill pipe sections
having at least one flattened portion, said apparatus com-
prising a platform swingably mounted on the drill table in a
plane generall~ normal to the axis of the drill pipe sect.ions,
said platform having an opening through which the drill pipe
sections are axially movable, a housing mounte~ on said
platform, a holding member slidably mounted in said housing
generally radially of said opening, said holding member having
means for cooperatively engaging the flattened portion of a
drill pipe section, means for selectively extending and
retracting said holding member, at least one stop member
mounted on the drill table in spaced relationship to said
opening and in a position to engage said housing when said
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platform is swung in one direction, whereby said holding
member is selectively movable into engagement with a drill
pipe section to prevent relative rotation between said member
and the drill pipe section.
In another aspect, the present invention provides
in a drill table having an opening through which a drill
pipe section having at least one flattened portion is axially
movable, said drill table being disposed generally normal to
the axis of said drill pipe section, the improvement com-
prising a platform swingably mounted on said drill table in a
plane generally normal to the axis of said drill pipe section,
said platform having an opening through which said drill pipe
section is axially movable, a housing mounted on said platform,
a holding member slidably mounted in said housing generally rad-
ially of said platform opening, said holding member having
one end located adjacent to said platform opening, said one end
including a recess of a size to cooperatively receive the
flattened portion of said drill pipe section, means for
selectively extending and retracting said holding member, at
least one stop member mounted on said drill table in spaced
relationship to said platform opening and in a position to
engage said housing when said platform is rotated in one
direction, whereby said holding member may be extended into
cooperative engagement with the flattened portion of
said drill pipe section to prevent relative rotation there-
between.
Brief Description of the Drawings
Fig. 1 is a top plan view with portions broken away
to show the wrench in retracted position.
Fig. 2 is a perspective view illustrating the wrench
in extended position.
Fig. 3 is a section on the line 3-3 of Fig. 2.
Fig. 4 is a section on the line 4-4 of Fig~ 2.
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J Fig. 5 is a top plan view showing the wrench in ex-
tended and rotated pos tion.
Descri tion of the Preferred Embodiment
Wi~h continued reference to the drawings, a conven~
tional drill rig (not shown) is provided wlth a high torque power
plant which is mounted on a frame and such frame ls mountPd for
generally vertical movement on ~he rig. Adjacent to the lower
en~ of the rig a drill table 10 is mounted in spaced relationship
to the earth. An opening 11 is provided in the table 10 and such
10 opening rotatably receives the collar 12 of a hollow tubular
sleeve 13. The inner diameter of the sleeve 13 is large enough
to permit a drill pipe secti~n 14 to move axially t:herethrough.
A platform 15 is welded or otherwise attached to the
upper portion of the collar 12 and such platform has an outer
periphery which overlies and rests on a portion of ~he drill
table 10. If desired, a plurality of anti-friction bear~ngs or
a bearing surface may be loeated between ~he perlphery of the
platform 15 and ~he drill table lO. Wi~h particular reference
to Fig. 3, two or more outwardly extending lugs 16 may be welded
20 or otherwise ~tached to the bottom of the collar 12 in over-
lapping relationship with a portion of the drill table 10 so
that the collar 12 cannot be acc~dentally or ea~ily removed from
the opening 11~ The platform 15 is provlded wi~h an elongated
tang or ex~ension 17 located generally radlally of the sleeve 13
and a housing 18 is welded or otherwise attached ~hereto.
A yoke or holding mem~er 20 is slidably mounted within
the housing 18 and such yoke is provided with a generally
U-shaped recess 21 in one end which is of a size to snugly re-
ceive the flattened portions of a drill pipe secti~n 14. The
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s:)pposite end of the yoke or holding member 20 has an elongated
slot 22 extending inwardly thereiErom and ~lermirla~ing ~ a pair
o shoulders 23 which are in spaced relation~hip to each other.
The shoulders con~nunicate with a dove~ail slot 24.
In order to extend and retract the yoke 20, a pair o
upstand~ng ear~ 25 are mounted adjacent to the outer end o~ the
tang 17 and such ears are conneeted by a pivot 26 to on~e end of
a fluid cylinder 27. Such fluid cylinder has an extend,able and
retractable pist~n rod 2~ with a generally frusto-conical pu~h-
pull head 29 mounted on its outer end. The head 29 i9 slidably
received within the dovetail slot 24 which confines the head in
back-and-orth directions. Fluid lines 30 and 31 connect the
opposite ends of the fluid cylinder 27 to a fluid motor and
reservoir (not shown) so that fluid under pres~ure can be selec-
tively introducf~d through either of the fluid lines and dis-
char~;ed throu~h the other fluid line to cause the piston rod 28
to be extended or retracted. Such 1uid lines extend through
openings 32 and 33 in the upper wall of the hou~ing 18 to the
fluld cylinder 27. If desired, the opening 32 may con~nunicate
20 with the irner edge o:f the houæing 18 by an inspection ~lot 34.
Ordinarily a pair of braces 35 are welded or otherwise attached -
to the platform 15 and one end of each of such braces is in
abut~ing rela~ionship with the hou~ing 18 to support the housing
against lateral movement or bending.
A palr o spaced stop members 36 and 37 are welded or
o~herwise rigidly a~tached ~o the drill table 10 and eaeh of such
stop members is provided wlith an impact face 38 wh:ich is disposed
generally radially of the sleeve 13 and subs tantially parallel
with the hous ing 18 when the housing is ro-tated irlto intimate
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engagement w~ th either of the impaet faces.
In the operation of the device, during the drilllng
operation, a plurality of drill pipe ~ections 14 are connected
together in end- to-end relationship by the threaded stud of one
drill pipe section being received within the opening of an adja-
dent drill pipe section. The uppermost drill pipe section is con-
nected to a threaded stud of the high tvrque power plant of the
drill rig so that rotation of the power plant cau~es rotation of
the drill string w~ich, in turn~ causes the cutter or drill bit
at the opposite end of ~he string to penetrate ~he earth. While
the power plant is rotating the drill string, the drill rig i9
lowering such power plant so that the drill bit continue~ to
penetrate the earth.
When the power plant has been lowered to a point
slightly above the drill table 10, the flattened portions adja~
cen~ to the upper end of the drill pipe section are allgned wi~h
the U-shaped recess o~ the yoke 20 after which the piston rod 28
i~ extended to cause the U-shaped recess to cooperatively re-
ceive the flattened portions of the drill pipe section. In thi~
20 posi tion the direction of rotation of the power plant is re-
versed to unscrew the power plant stud from the drill pipe sec-
tion and if the threaded connection ~s broken the po~er plant
stud is unscrewed after which the power plant is raised to re-
ceive another drill pipe sectlon which is then screwed into the
drill pipe section being held by the yoke 20.
If the rever~ing of the power plant should fail to
break the threaded connection between the puwer plarlt stud and
the drlll pipe sectlon, the power plant is rotated irl a screw~g
direction. Since t~e drill pipe section cannot rotate relative
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to the yoke 20, the platform 15 is rota~ed within the opening 11
until the housing 18 engages one of the stop members 36 or 37.
At this polnt the direction o rotation of the power plant is
rever~ed and operated rapidly in an u~screwing direction which
causes th~ housing 18 to swing around and engage the other stop
member wi~h a hard impact. The torque of the power plant normally
is sufficient to break the threaded c~nnection between the power
plan~ stud and the drill pipe section.
After the drilling operat~on has bee~ completed, or when
it is necessary to change the drill bit at ~he lower end of the
drill ~tring, the power plant is raised so that the drill string
i9 lifted until the uppermost drill pipe section is located above
the drill table 10 and the ~lattened portions oE the next sub;a-
cent pipe sectio~ are in alignment w~th the yoke 20. At this
time the yoke is extended into engagem~nt with the subjacent drill
pipe sectlon. The power plant th0n is rotated in a screwing dir-
ect~on to cause the platfonm 1~ to rotate so ~hat the housing 18
engages one of the stop members after which the directlon of
rotation of the power plant i5 reversed to swing the platform in
the opposite direction and strike the impact face of the other
~top member with a hard impact force.
I~ is noted that the thread~ of the power plant stud
are in the same direc~ion as the threads on the lower end of the
drill pipe section; however, when the power plant is rota~ed in
an unscrewing direction, the torque which is applled ~o the upper-
most drill pipe section and the sudden impact ad~acent to the
connection between the uppermost dr~ll pipe section and the next
adjacent drill pipe section causes the threaded connlection be-
~tween drill pipe sections to break instead of breaking the con-
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nection between the upper end o the drill pipe section and the
power plsnt stud.
After the threaded connection between the drill pipe
sections has been broken, continued rota~ion o~ the power plant
unscrews the upper pipe sec~ion from the drill string after which
the separated pipe section may be placed i.n a rack and discon-
nected fr~m the power plant. The power pl.ant then is lowered so
~hat the power plant s~ud threadedly engages the opening in the
upper end of the drill pipe section being held by the yoke after
wh~ch the yoke is retracted, the power plant is raised to lift
the drill string again, and the operation is repeated.
